Using the behavior change wheel to design a novel home‐based exercise program for adults living with overweight and obesity: Comprehensive reporting of intervention development

Abstract Introduction Physical activity and exercise are movement behaviors that support the lifestyle management of overweight and obesity. However, home‐based exercise programs are commonly generic, and inconsistently undertake a holistic approach to program design. Methods This work applied the Behavior Change Wheel, supplemented with previously conducted interviews, to the development of a home‐based exercise program, specifically for people living with overweight and obesity. This provided an understanding of the target behavior and identified a behavioral diagnosis. These findings were mapped onto the Capability, Opportunity, Motivation‐Behavior model and Theoretical Domains Framework, identifying changes needed and corresponding intervention functions. Results Suitable Behavior Change Techniques were identified, alongside Capability Opportunity Motivation‐Behavior components needed to facilitate an increase in exercise behaviors, and five key intervention functions. This housed the delivery of 24 Behavior Change Techniques, including goal setting, feedback, monitoring and repetition. Conclusion Applying the Behavior Change Wheel has enabled detailed development of a home‐based exercise program for adults living with overweight and obesity.

Routinely, adults wishing to engage in physical activity and exercise behaviors do so through access to leisure facilities and community centers. 1 However, specifically for adults living with overweight and obesity, exercising within the home may also be more comfortable, without the presence of exercise stigma or shame often present within a gym setting. 2 Whilst the flexibility of home-based exercise also suggests a suitable and popular alternative, there is limited evidence of the design of home-based exercise programs tailored to the needs of adults living with overweight and obesity. 3The prescription of a generic exercise program lacks individualization for participants with additional health needs that may require a more needs-sensitive program, where considerations are made for additional factors than just the immediate program content.This may include the exercise type, mode of delivery, or exercise intensity.This highlights the need for the design of a population-specific home-based exercise program specifically for adults living with overweight and obesity.
The design process of interventions encouraging behavior change should be theory informed, 4 and consider the identification and incorporation of suitable Behavior Change Techniques (BCTs). 5ilst the evidence for effectiveness of theory-based interventions is mixed, 6 as each selected theory may not contain all the necessary constructs to facilitate behavior change, 7 there are many recommendations, including comprehensive reporting, contributing towards increased evidence. 8Despite the myriad of evidence of the benefits of physical activity and exercise for health, this is not reflected in adherence and engagement statistics where physical activity behavior has not improved since 2001. 9In addition, limited literature reports on the integration of a behavior change framework within home-based exercise program design, specifically for adults living with overweight or obesity, further highlighting the need to further explore this aspect of program design and development.
The Behavior Change Wheel (BCW) facilitates broad consideration of different behavioral options at different populations, 10 preventing design commitment to a certain BCT without fully exploring different frameworks and techniques that may not have been considered otherwise.Figure 1 presents the BCW dissected further within Figures 1A-C.Specifically, regarding adults living with overweight and obesity and the current scarcity of needs-sensitive homebased exercise programs, a theoretical framework that prompts wide consideration of participants' needs would be deemed most appropriate to apply in this intervention design.

| Overview
The BCW was applied to inform the development of a home-based exercise program for adults living with overweight and obesity.It followed the application of three important stages, as previously defined, 10 combined with evidence from current literature and qualitative data from previously conducted interviews with adults living with overweight and obesity. 11No ethics approval was required due to the nature of this secondary data work and for the supplementary interviews, ethics approval was granted by the Coventry University Ethics Review Committee (Reference: P123487).Figure 2 provides an overview and application of the method.

| Stage one: Understanding the behavior
Stage one considered specific behavioral contexts of the problem, including the social and environmental context in which this behavior occurs as well as the individual, group, or population of focus.This included a review of relevant literature and exploring experiences and preferences of home-based exercise for adults living with overweight or obesity through semi-structured interviews, which have been previously reported within the literature. 11The identified themes and codes from the interviews were mapped onto the Capability, Opportunity, Motivation-Behavior (COM-B) model (displayed in Figure 1A), which informed the behavioral analysis and supported the consideration of BCTs to best encourage behavior change.This process allowed us to identify sources of behavior involved in exercise related choices specifically in adults living with overweight and obesity.

| Stage two: Identifying intervention options
Following stage one, the BCW framework informed the chosen intervention functions, supported by literature, most likely to initiate behavior change within each COM-B component.All intervention functions within the BCW and subsequently considered in this intervention development are displayed in Figure 1B.
The APEASE criteria (Affordability, Practicability, Effectiveness, Cost-effectiveness, Acceptability, Side-effects and Safety) were used to further determine the appropriateness of the chosen intervention functions.Supporting policy categories were then selected to maximize the potential of successful behavior change by enabling the chosen intervention functions to occur where links between intervention and policy categories were present. 12The policy categories in the BCW are displayed in Figure 1C.

| Stage three: Intervention content
From the extensive list of 93 possible BCTs within the BCT Taxonomy v1, 13 the authors selected techniques, justified by the previous stages detailed above, deemed to be most feasible and effective in

| Stage one: Understanding the behavior
The identified target behavior was to increase exercise in adults aged 18-64 years living with overweight and/or obesity.The identified environment was the place of residence or the immediate vicinity such as the garden and/or driveaway, in accordance with the definition of home-based exercise as previously defined. 15In line with global physical activity recommendations, 16 achieving increased physical activity through a 12-week home-based exercise program was deemed an appropriate target behavior by the research team.This could be undertaken at any time of the day, where in program weeks 1-9 would be 3 times per week, weeks 10-12 would be 4 times per week.To further understand the behavior of home-based exercise, experiences and preferences of home-based exercise were previously explored through semi-structured interviews. 11From this, the generated themes and codes that facilitated and impeded homebased exercise were mapped against the COM-B model, which can be seen in more detail in Supplementary Material one and the previously conducted semi-structured interviews. 11ychological capability.Both the interview data and the literature reported similar barriers to exercise.Participants reported that not knowing where to start was a key barrier, demonstrating similarity to existing and current research. 17,18ou know you can be over ambitious in what you're doing and actually end up hurting yourself and I don't want to do that.I want to stay as healthy as I can and [my] knowledge of exercise is not very great." Possessing psychological capability, where in this work capability would be demonstrated through knowledge surrounding exercise, is important in making and sustaining behavioral change. 19rticipants reported that a key facilitator of exercise was awareness of the psychological and physiological benefits of participation.Participants commented on the impact of this understanding on their exercise behavior, which is further reinforced within literature, 20 where an awareness of the benefits of physical activity and exercise influences behavioral choice.

Physical capability.
In the interview, a key barrier to exercise was the participant's physical exercise environment.Participants made reference to reduced physical space influencing their choice of, and engagement with, home-based exercise.Similar findings were found within the literature, suggesting that individuals lacked sufficient space to be physically active, subsequently impeding exercise engagement. 21This may also link to the participant's psychological capability through reduced knowledge of how to exercise within their home environment.
Physical opportunity.Participants also reported that other responsibilities and commitments may take precedence over participation in exercise.Reduced time was a large barrier which would impact on engagement but conversely highlights home-based exercise as a potential solution.One participant said: "Some of my other colleagues would go to the gym and I couldn't be bothered to do it so I that's why I did it at home.

Time wise it saves a lot time."
Further reinforced within the literature, the reduction in perceived, or actual, physical opportunity has been determined as a barrier to engagement in exercise. 22With consistent recognition that 'lack of time' could be an actual or perceived barrier by participants.
Another barrier to partaking in a home-based exercise program was the physical environment in which the participants would conduct the exercise; not having sufficient space or the necessary equipment to conduct specific exercises were both barriers to participation.This recognition is also present within additional literature, similarly concluding that limited space and/or appropriate equipment does negatively impact exercise engagement. 23cial opportunity.Social support within exercise and physical activity has been seen as a facilitator of physical activity. 24Interview participants reported that social support from friends and family was a facilitator for engaging in a home-based exercise.One participant demonstrated this through a relationship with their children and for some, this home environment offers participants social opportunity and subsequent increased engagement in home-based exercise. 25wever, for those that are isolated and use community-based exercise for social opportunity, this may be a barrier to increasing exercise behavior.
Participants also reported the importance of a sense of community through undertaking group exercise, not only focusing on the exercise itself but also the opportunity to be part of an online/virtual community with others.
"If there's no social element to it and I can't talk to somebody, then I find that very difficult." The relationship between engaging in exercise and COM-B categories, especially social support, is also recognized within the literature. 26Highlighting that a lack of social opportunity can be a barrier to exercise engagement.
Reflective motivation.Participants spoke of components in their lives that motivated them to undertake and continue exercise engagement.These motivators varied, but commonly included family members, fitness instructors and biofeedback from wearable technologies.

"Having a watch that buzzes every half an hour and says move is no bad thing."
Similarly found within the literature, the result of biofeedback technologies encourages participants to lead a more active lifestyle, increasing awareness of their current lifestyle with a view for alteration. 27tomatic motivation.Enjoyment of exercise was identified as a key influence on exercise participation.One participant spoke of their enjoyment of exercise as the primary motivator for engagement.Receiving enjoyment through exercise contributed toward a positive feedback loop of continued exercise engagement, gradually making exercise habitual.This habitual, automatic motivation within the context of exercise has also been reported in the literature. 28ese barrier and facilitator codes above have been mapped onto the COM-B and further explored using the Theoretical Domains Framework (TDF), which can be seen in Table 1.This process facilitates comprehensive consideration within the selection and

| Stage two: Identification of intervention options
The process of deeming intervention functions as suitable or nonsuitable was through using the APEASE criteria.Intervention functions deemed suitable were Education, Training, Modeling, Enablement and Environmental restructuring and therefore deeming Persuasion, Incentivisation, Coercion and Restriction as unsuitable and subsequently excluded.Further details on this process can be found in Supplementary Material two.
The selected intervention functions were also matched with the COM-B and TDF most likely to be effective in changing exercise behavior.This can be found in Supplementary Material three.Subsequently, the APEASE criteria was also used to explore suitable policy categories, alongside the intervention function and COM-B components, as well as how this could be applied to a Home-Based Exercise Program (HBEP).The outcome and application of this process are displayed in Table 2.

Integration of technology (F) Physical skills
Change is not needed

Change is needed
Participant's physical environment may not facilitate HBEP.
Creation of opportunities for participants to be active at home.

Change is needed
Participants may lack a support network.
Create opportunities for participants to network with others on the HBEP for social support.

Source of accountability and motivation (F) Progress monitoring and biofeedback (F)
Social/professional role and identity Change may be needed Some participants may not know the benefits of being physically active.Some participants may already know but do not, or are unable to, act upon their knowledge.
Believe that increasing physical activity is beneficial for their health.

Optimism
Intentions Believe that they have the capability to undertake home-based exercise.Goals

Enjoyment of the exercise (F)
Variety is key (F) Uncontrollable barriers (F)

Reinforcement Emotion
Change is needed Habit formation may not be established, preventing prolonged engagement in exercise.
Make engagement in the HBEP habitual.
Abbreviations: COM-B, Capability, Opportunity, Motivation, Behavior; TDF, Theoretical Domains Framework.3 shows the complete application of the BCW in the design of a HBEP specifically for adults living with overweight and obesity.

| DISCUSSION
This study details the development of a home-based exercise program for adults living with overweight and obesity using the BCW.
The BCTs identified throughout the development process will supplement the design and delivery of a 12-week online home-based T A B L E 2 Use of the APEASE criteria to identify suitable policy categories with complementary intervention functions and COM-B components.

Education Physical and psychological capability Communication/ marketing
Yes, this can encourage exercise.Printed and online materials can be incorporated.

Reflective motivation Guidelines
Yes, there will be a standardized HBEP for participants whilst also providing evidence to support the use of the program.

Psychological capability, physical opportunity
Regulation Yes, long-term establishment of home-based exercise principles of behavior and practice.

Training Physical capability Communication/ marketing
Yes, current national guideline materials provide rationale for the HBEP.

Guidelines
Yes, standardized HBEP will include guidelines that recommend practice.

Physical opportunity Environmental planning
Yes, individuals will create a space to exercise safely.

Service provision
Yes, provide individuals with an exercise program and offer equipment and supervision.

Social opportunity Communication/ marketing
Yes, provide opportunity to create a social network with other participants.

Modeling Physical capability Communication/ marketing
Yes, communicate and regulate the exercise conducted and correct technique.

Guidelines
Yes, detailed exercise instructions with imagery.

Physical opportunity Communication/ marketing
Yes, communicate and regulate the exercise by modeling with correct technique.

Communication/ marketing
Yes, long-term collective action to overcome barriers to adherence and participation.

Social opportunity Service provision
Yes, provide a platform for individuals to connect with others.

Physical opportunity Environmental planning
Yes, alter space to ensure exercise safety with addition of equipment if required.

Automatic motivation Communication
Yes, long-term habit formation.

Physical opportunity Communication
Yes, encourage individuals to create a suitable environment for participation, with ease of access and without obstructions.vention may be deemed impractical; however, due to the complex nature of this intervention, all 24 BCTs have a role within the HBEP.

Reflective motivation
The identified BCTs also reflect those deemed to be more effective in recent systematic reviews within physical activity and exercise program design and prescription. 32,33

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POWER ET AL.eliciting the desired behavior change.The list was created by reviewing the evidence on effective techniques for increasing adults' physical activity and exercise,14 and mapping these BCTs to the intervention functions.The practical application and delivery of the intervention were discussed and thoroughly reviewed by the research team, identifying BCT implementation errors, and assessing their feasibility.Tracked changes were used to record each iteration of the subsequently developed program until a consensus was reached.

F I G U R E 1
Segmented behavior change wheel.(A) The COM-B components of the behavior change wheel; (B) intervention functions of the behavior change wheel; (C) policy categories of the behavior change wheel.F I G U R E 2 Overview and application of the method, with stages and steps from the BCW Blue text denotes steps as defined by Michie. 10APEASE criteria, Acceptability, Practicability, Effectiveness, Affordability, Spill-over and Equity; BCW, Behavior Change Wheel; COM-B, Capability, Opportunity, Motivation, Behavior; HBE, Home-Based Exercise; HBEP, Home-Based Exercise Program; TDF, Theoretical Domains Framework.POWER ET AL.

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POWER ET AL. application of evidence-based practice.The behavioral diagnostic process concluded that the most suitable components and domains were psychological and physical capability, social and physical opportunity, and automatic and reflective motivation.

T A B L E 1
Further exploring the COM-B and qualitative codes through TDF and identifying the needs to facilitate behavior change.Participants may not have knowledge of specific exercises and correct technique.Gain knowledge of program specific exercises and correct technique.Cognitive and interpersonal skills Memory, attention and decision processes Knowledge of the potential benefits of taking part in the HBEP.

3 |
Stage three: Intervention content Within the five chosen intervention functions (education, modeling, enablement, training and environmental restructuring), a total of 24 BCTs were deemed appropriate by the research team, derived from the intervention development process and the appropriateness to the home-based exercise program.The mode of delivery for these BCTs is via the HBEP delivered through Hope for the Community, an online self-management platform for health interventions, providing easy access to participants, in which feasibility for other noncommunicable diseases have been demonstrated. 29Altogether, the Health at Home with Hope home-based exercise program incorporates 24 BCTs across five intervention functions.The selected BCTs with official definitions and generic application to an exercise intervention are shown in Supplementary Material four.The BCTs and intervention functions correspond to COM-B components, theoretical determinants, policy categories and HBEP-specific intervention strategies.Table Implementing the BCW during program design has supported the research team to consider the full array of techniques contributing toward program adherence, engagement and long-term behavior change.10The development of this complex program requires further consideration to just prescribing exercises,30,31 and the BCW prompted exploration of different techniques that could facilitate that.It provided an opportunity to deeply consider and explore less obvious design features of the home-based exercise program, to a further extent than what would have been undertaken without the application of the BCW.The inclusion of 24 BCTs across an inter-

a 4 . 1 |
Represents repeated BCTs under different intervention functions.solely prescribes exercise.Whilst all participants will have different circumstances and lifestyle considerations that will impact their ability to undertake and engage in a HBEP, designing a program that aims to account for these through BCTs provides an opportunity for participants to access a program that they can tailor to best suit their individual needs.To the authors' knowledge, the implementation of the BCW in the design and development of an HBEP for adults living with overweight and obesity is novel within the peer reviewed literature in this research area.It allows for further consideration of BCTs in comparison to exercise programs designed without, with scope to positively impact program engagement and adherence.The detailed reporting of how the BCW was used within the programmed design for this home-based exercise program throughout this study is a strength.There is limited literature available that comprehensively details the specific rationale and method of identifying and integrating BCTs into exercise interventions that include behavior change elements.Literature typically only reports the inclusion of BCTs but does not detail how or why those techniques were chosen.Without this, intervention development lacks robustness and decreases the chance of success when the program is implemented.Therefore, the detail in this paper contributes toward ease of repeatability by other researchers or health professionals looking to apply a theoretical behavior change framework within exercise program design as well as increased program success.It also provides the necessary detail to inform stakeholders, regardless of their specific intervention content, of the application and integration process of a behavior change framework within program design, subsequently improving the application and reporting of this process within the field.Whilst we have tried to integrate appropriate BCTs into the design of the program, in order to account for lifestyle variability between participants, we recognize that not all the techniques will be appropriate and/or effective for all participants.Part of this process may also include a continual open dialogue with stakeholders in the program design and development process.This will allow for an iterative refinement process of the program and associated materials as well as evaluation of program aspects to further improve the output.Despite this, it can be challenging to develop a program that will suit a constantly growing population group, and therefore we understand that whilst this program aims to be helpful for the majority, we do recognize that participants may find elements of the program unhelpful.Whilst this may not be a limitation in its truest sense, the recognition of tailoring to different needs by researchers still remains important.Future directions Future program development research should aim to further tailor and develop home-based exercise programs for adults living with overweight and obesity to facilitate maximum program flexibility and increase program engagement and adherence.This would include interaction with people with lived experience, both with regard to the content of the developed program itself and also how program flexibility and engagement can be simultaneously achieved.We also widely encourage future use of a behavior change framework in the design of exercise programs.Whilst we recognize that the BCW may not be suitable for all intervention development processes, a behavioral framework would facilitate a wider consideration and a targeting of factors that influence participant engagement and adherence and subsequently, program success.In addition to using a behavior change framework in intervention design, thorough reporting of the process should also be encouraged.Dissemination of the design process would aid researchers, developers and practitioners to learn about the whole process rather than just the finished project.For example, this may be through research team links to national and regional physical activity networks, local authorities, charities, and organizations that focus on obesity.The need for comprehensive reporting and choice justification, when using behavior change strategies, within intervention designs aligns with the work of Biddle et al.34They have highlighted the current lack of explicit detail and justifications for the theoretical underpinnings of interventions, with even fewer stating how the chosen theory links to the behavior change strategies.This work details the application of the BCW in the design and development of a home-based exercise program for adults living with overweight and obesity.It specifies the implementation of a theoretical behavior change framework and explains how this contributes to an informed and considered program design.The research team encourages others to do the same when designing and implementing exercise programs.Specifically, within overweight and obesity, where long-term program adherence and engagement are inconsistent, considering a behavioral change framework within the intervention design phase is likely to increase the chances of program success.

component Theoretical determinants BCTs with implementation schedule Policy categories Specific intervention strategy
Complete application of the BCW in the design of a HBEP specifically for adults living with overweight and obesity.